Outboard motor supporting bracket



March 13, 1962 c. R. CORBIN, JR, ETAL 3,025,028

OUTBOARD MOTOR SUPPORTING BRACKET Filed June 26, 1958 INVENTORS' ATTORNEY Filed June 26, 1958, Ser. No. 744,782 2 Claims. (Cl. 248-4) This invention relates to improvements in outboard motor mountings, and more particularly to a mounting plate to be associated with the transom of a boat to support the outboard motor.

A main object of the invention is to provide a supporting bracket which is vertically adjustable and will support the motor in a plurality of vertically adjusted position whereby to vary the depth of the propeller with respect to the bottom of the boat and the water line thereof.

A further object of the invention is to provide such a motor-supporting bracket which is substantially incapable of being ripped from the boat transom as by unusual motor thrust or like cause in which event would cause the loss of the motor overboard, which is not unusual and is now prevalent in the known mounting brackets.

A further object of the invention is to provide a supporting bracket which is vertically adjustable in a manner to always be in association with the underside of the normal outboard motor bracket, and by using various size shims which are spaced between the top of the transom and the outboard motor carrying bracket, will securely support the motor at all times.

Other objects and advantages will be apparent when considered in the light of the accompanying detailed description and drawings, in which:

FIG. 1 is a side elevation partly in section showing the outboard motor mounted in its lowermost position;

FIG. 2 is a view similar to FIG. 1 showing the outboard motor in its furthest raised position;

FIG. 3 is a front face view showing a portion of the transom and the adjustable mounting bracket; and

FIG. 4 is a perspective view of the supporting bracket.

In the drawings, in which like numerals are used to indicate corresponding parts throughout the various views, only the rear portion of a boat is shown, and it is to be understood that the boat might be of the normal rowboat type, or of the more recent so-called run-about type, which is normally propelled by a removable outboard motor. Thus, in the drawings, the bottom of the boat is indicated at 6 and the transom thereof is shown at 7.

An outboard motor of usual type is generally indicated at 8 and is provided with the normal vertical casing 9 containing the drive shaft to the propeller 10, said motor being provided with the usual U-shaped clamping bracket 11, the bracket 11 including two U-shaped arms 12 and 13 having a rear somewhat flattened portion 14 engaging the rear surface of the transom 7 and each of the brackets provided at their front extremities with clamping screws 15 and 16, said clamping screws being provided with normal operating bolts 17 and terminating in clamping shoes 18, said clamping shoes being capable of engaging the inner surface of the transom 7, or as in the present case engaging the recesses 22 and 23 provided in the clamping bracket of the present invention. The arms 12 and 13 of the U-shaped bracket 11 are normally spaced by a sleeve member 19 mounted on a bolt arrangement 20.

The mounting bracket or supporting plate of the present invention is generally illustrated at 21 and may be made of various type metals or other hard composition material, but preferably the bracket is made of light-weight ite States atenr 3,@Z5,fi28 Patented Mar. 13, 1962 aluminum, to save weight. The bracket is provided with two spaced recesses 22 and 23 which are adapted to receive the members 18 on the clamping screws 15 when the bracket is mounted in place on the transom. Further, the bracket is provided with a plurality of vertically disposed bolt-receiving slots 24, 35 and 26. These slots are adapted to receive bolts 27, 28 and 29, the bolts being of the usual round-headed type and being fastened as by the normal type nuts and washers. As illustrated in FIG. 1, the mounting bracket 21 is shown fastened to the inner side of the transom as by the bolts 27, 28 and 29 which are mounted in drilled holes in the transom and passed through the respective vertical slots of the bracket. In this figure, the top of the mounting bracket 21 is fiush with the upper surface of the transom and thus, when the outboard motor is mounted on the transom the U- shaped brackets 12 and 13 engage the upper surface of the transom and likewise the upper surface of the supporting bracket 21. Now, when it becomes desirable to raise the outboard motor with respect to the transom, it is only necessary to loosen the nuts on the. respective bolts supporting the bracket, after which the bracket can be vertically raised, and in this position would extend above the uppermost top surface of the transom whereupon the bolts and nuts canbe tightened to support the bracket in any one of several vertical positions. This being done, a shim 30, substantially the same width as the transom and normally made of oak or other hard material, of course, it could be metal, is then driven or inserted between the top of the transom and undersurface of the U-shaped brackets, the top of the shim registering and coinciding with the top of the mounting bracket to give a flush surface upon which rests the undersurfaces of the motor brackets. Such a position is illustrated in FIG. 2 and consequently it will be seen that the depth of the motor and its propeller with respect to the bottom of the boat and the water line of the boat has been moved vertically or nearer the surface of the water. It will, of course, be understood that various sized shims can be used depend ing upon the vertical adjustment of the supporting bracket 21 and consequently the motor and propeller can be moved to a plurality of vertical positions depending on the number and thickness of the shims used and likewise depending upon the vertical position of the supporting bracket 2i.

It has been found and discovered that in the use of an outboard motor, especially upon fast run-abouts, that the position of the propeller with respect to the surface of the water is critical, insofar as the ability of the outboard to drive the boat at various speeds is concerned; that is, it has been found that some boats can be propelled faster through the water if the motor is adjusted more closely to the surface of the water, while other boats can be propelled faster if the propeller is deeper in the water, and not so near the surface. At certain high speeds, it has been determined if the position of the propeller is not accurate, that the same will cavitate or cause cavitation which of course detracts from the efficiency of the propeller and likewise from the speed of the boat. Such cavitation is dependent upon many things and so it varies with respective boats. Thus, the load in a boat will vary the ability of the propeller to cavitate and consequently various vertical adjustments are necessary to take care of the same. It also has been found that various wind and water conditions will vary the cause of cavitation of a propeller and therefore it is desirable to provide means to adjust the propeller vertically to a position to obtain the best results, that is, the fastest speed at which the boat is capable of being propelled.

With the present invention it will be readily recognized that with an adjustable bracket of the type disclosed and with the use of a number of various sized shims, that the operator of a boat can try the same and through manipulation determine the best position of the propeller for obtaining the highest speed possible with the particular motor used.

It is not uncommon in the use of an outboard motor and especially at high speed, for the motor to throw itself from the transom, this being occasioned by the terrific motor thrust and pressure developed at the supporting bracket. Normally, the usual outboard motor bracket is simply positioned on the transom and the clamping screws tightened and, consequently, the clamping screws through vibration can work loose, and it is not uncommon to have the motor disengaged from the transom and consequently go overboard and involve a costly and long procedure in recovering the motor. With the present invention, this is substantially impossible in view of the fact that the mounting bracket 21 is actually bolted and clamped to the transom by the three bolts 27, 23 and 29, and further, the supporting bracket 21 being provided with the cup-shaped recesses 22 and 23 to accommodate the clamping members 13 help to prevent the possibility of the motor being disengaged from the transom. Thus, with our construction the supporting bracket or plate is made substantially integral with the transom and it is substantially impossible for the motor to move with respect to the transom after the same has been clamped thereon.

However, of course, it will be readily understood that the main feature of the invention is the feature that the supporting plate or bracket 21 is vertically adjustable to thereby adjust the vertical position of the propeller with respect to the water line and thereby obtain the best results possible in the propulsion of the boat.

It is to be understood that the invention is not limited to the exact construction shown but is capable of variation within the scope of the following claims.

We claim:

1. A mounting bracket for adjustably supporting an outboard motor to a boat, said boat having a transom and a bracket mounted on the inner surface of the transom, said bracket having a plurality of vertically disposed slots extending therethrough, a plurality of bolts extending through the transom and through the slots, fastening members mounted on the bolts to lock the bracket to the transom in selective vertically disposed positions, and an outboard motor having a pair of fastening brackets extending over the transom and engaging the uppe surface of the adjustable bracket, 21 pair of cup-shaped recesses in said bracket positioned to receive a pair of clamping members, said outboard motor bracket having a pair of fastening screws engaging said cup-shaped recesses on the front face of the adjustable bracket.

2. The combination recited in claim 1, and a removable shim positioned along the upper edge or" the transom and engaging the under side of the outboard motor bracket, when the mounting bracket is raised above the transom height.

References Cited in the file of this patent UNITED STATES PATENTS 1,389,712 Thompson et a1. Sept. 6, 1921 2,379,256 Schleisner June 26, 1945 2,527,904 Baldwin Oct. 31, 1950 2,713,842 Plouff July 26, 1955 2,756,953 Button et al. July 31, 1956 2,815,731 Curtis Dec. 10, 1957 

